TextMentionTermination(sources=...) drops sources on dump_component / load_component

Describe the bug

TextMentionTermination(..., sources=[...]) scopes which speakers can trigger the stop text (see #4807). On dump_component / load_component, sources is omitted from the config, so after restore the filter silently matches any source — including the user prompt that was supposed to be ignored.

To Reproduce

import asyncio
from autogen_agentchat.conditions import TextMentionTermination
from autogen_agentchat.messages import TextMessage

async def main() -> None:
    t = TextMentionTermination("TERMINATE", sources=["writer"])
    assert await t([TextMessage(content="please TERMINATE", source="user")]) is None
    await t.reset()
    assert await t([TextMessage(content="TERMINATE", source="writer")]) is not None

    cfg = t.dump_component()
    print(cfg.config)  # {'text': 'TERMINATE'}  — no sources

    t2 = TextMentionTermination.load_component(cfg)
    stop = await t2([TextMessage(content="please TERMINATE now", source="user")])
    assert stop is not None  # BUG: user message now terminates

asyncio.run(main())

Also reproduced when nested in TextMentionTermination(...) | MaxMessageTermination(5): nested dumped config still only has text.

Expected behavior

Config includes sources; restore keeps sources=["writer"]; user messages containing the phrase do not stop the run.

Actual behavior

TextMentionTerminationConfig only serializes text. _sources becomes None after load, so the filter widens to all speakers.

Environment

• autogen-agentchat 0.7.5
• Python 3.13

Additional context

This makes declarative save/load unsafe for any team that relies on sources to avoid premature stop from user text.